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SYFY WIRE Paleontology

Check out the humongous horned shell on this rare prehistoric turtle

By Jeff Spry
Turtle Hero

Wearing a horned shell measuring nearly ten feet long, paleobiologists hailing from the University of Zurich have discovered fossils of a monstrous extinct freewater turtle in South America that once swam the swampy, tropical waters of ancient Venezuela and Columbia some eight million years ago during the Miocene Epoch. 

The massive carapace of the species, known as Stupendemys geographicus, is believed to be the largest ever found on Earth, and has been identified as belonging to an adult male due to the unique horned structures displayed on its saucer-shaper shell. Its remains were found in what is now a much drier, desert region of Venezuela that has proved to be fertile grounds for giant prehistoric rodent and crocodylian fossils.

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"The carapace of some Stupendemys individuals reached almost three meters, making it one of the largest, if not the largest turtle that ever existed," says lead study author Dr. Marcelo R. Sánchez-Villagra, director of the Paleontological Institute and Museum of UZH. "The two shell types indicate that two sexes of Stupendemys existed – males with horned shells, and females with hornless shells. The species likely achieved its colossal size thanks to the warm wetlands and lakes in its habitat."

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This provocative new research paper was published last week in the online scientific journal, Science Advances. With a calculated body mass weighing approximately 2,524 pounds, this burly aquatic beast is almost one hundred times the bulk of its nearest living relative, today's big-headed Amazon river turtle.

Scientists have been well aware of the ginormous S. geographicus turtle since back in 1976 when the first specimen was unearthed, but this enlightening new investigation has revealed a bounty of fresh fossils and previously unknown secrets about this colossal super-turtle. 

Chomp marks and punctured bones in the shell also pointed to violent interactions with aggressive caiman predators that also made these swamp waters in the northern Neotropics their home. And with a crusty shell of that size, this tasty turtle would be much more than a mouthful for any hungry foe!

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